e045dddae8
This change fixes the dependencies between the clock implementation headers. All the clocks share the common clock offset, but are otherwise independent (though the `db_clock` does depend on `gc_clock` for time point conversions).
68 lines
2.3 KiB
C++
68 lines
2.3 KiB
C++
/*
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* Copyright (C) 2014 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "clocks-impl.hh"
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#include "gc_clock.hh"
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#include <chrono>
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#include <cstdint>
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#include <ratio>
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#include <type_traits>
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// the database clock follows Java - 1ms granularity, 64-bit counter, 1970 epoch
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class db_clock {
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public:
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using base = std::chrono::system_clock;
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using rep = int64_t;
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using period = std::ratio<1, 1000>; // milliseconds
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using duration = std::chrono::duration<rep, period>;
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using time_point = std::chrono::time_point<db_clock, duration>;
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static constexpr bool is_steady = base::is_steady;
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static std::time_t to_time_t(time_point t) {
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return std::chrono::duration_cast<std::chrono::seconds>(t.time_since_epoch()).count();
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}
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static time_point from_time_t(std::time_t t) {
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return time_point(std::chrono::duration_cast<duration>(std::chrono::seconds(t)));
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}
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static time_point now() {
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return time_point(std::chrono::duration_cast<duration>(base::now().time_since_epoch())) + get_clocks_offset();
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}
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};
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static inline
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gc_clock::time_point to_gc_clock(db_clock::time_point tp) {
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// Converting time points through `std::time_t` means that we don't have to make any assumptions about the epochs
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// of `gc_clock` and `db_clock`, though we require that that the period of `gc_clock` is also 1 s like
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// `std::time_t` to avoid loss of information.
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{
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using second = std::ratio<1, 1>;
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static_assert(
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std::is_same<gc_clock::period, second>::value,
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"Conversion via std::time_t would lose information.");
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}
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return gc_clock::from_time_t(db_clock::to_time_t(tp));
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}
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